A diaphragm pump of this type includes a motor serving as a driving source, a crank that rotates upon driving of the motor, a driving shaft fixed to a portion displaced from the rotation center of the crank while having one end tilted with respect to the rotation axis of the crank, a driver having a non-through hole for receiving the other end of the driving shaft and pivotally supported by the driving shaft to be rotatable, and a diaphragm to which a diaphragm portion configured to form a pump chamber at each oscillation end of the driver is attached (see patent literature 1).
In the diaphragm pump described in patent literature 1, when the crank rotates upon driving of the motor, the driving shaft rotates about the output shaft of the motor while changing its tilt direction. The oscillation ends of the driver thus sequentially reciprocally move. Hence, the pump chambers sequentially expand and contract. When the pump chamber expands, air is sucked from the atmosphere into the pump chamber. When the pump chamber contracts next, the air in it is supplied to a pressurization target such as a sphygmomanometer.